Studies on rabbit bactericidal factors: Goals for the current year include the following: (1) Further characterization of the non-lysozyme bactericidal factor(s) in NRS, (2) their specificity, (3) cellular source, and (4) mode of action. Extraction of active material from the cellular source as a possible means of purification will also be investigated. Rabbit lysozyme will be examined for (1) its enzymatic activity in relation to other lysozymes, (2) its bactericidal capabilities, as well as (3) possible amino-acid and sequence analysis. Studies on human bactericidal factors: The major goals of the investigation for the coming year are (1) to determine the spectrum of activity of the non-lysozyme factor purified from lymph and plasma, (2) to determine the contributions made by this factor and lysozyme, respectively, to the intact bactericidal system, and (3) to investigate the biochemical mechanisms active in the bactericidal reaction.